#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int arr[10];
	int hash1[10] = { 0 };
	int hash2[10] = { 0 };
	int i = 0;
	int j = 0;
	int k = 0;
	for (i = 0; i < 10; i++)
	{
		scanf("%d", &arr[i]);
	}
	for (i = 0; i < 10; i++)
	{
		int mid = 0;
		for (j = 0; j <= k; j++)
		{
			if (hash1[j] == arr[i])
			{
				mid++;
				hash2[j]++;
				break;
			}
			if (arr[i] != hash1[j] && j != k)
			{
				continue;
			}
			else
			{
				hash1[j] = arr[i];
				hash2[j]++;
			}


		}
		if (mid)
			continue;
		else
			k++;
	}
	for (i = 0; i < k; i++)
	{
		if (hash2[i] == 1)
			printf("%d \n", hash1[i]);
	}
	return 0;
}